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Thursday, September 20, 2012

Project Objective: In this project we will use the Arduino to emulate the PH
Anderson #117 serial text display minus big numbers. The layout of a piggyback pcb
will complete the project.

Introduction: See
the discussion in the "Controlling a Serial Display" project which
covers several of the serial LCD displays on the market. Most of these products
have a similar command set and the sketch presented here could be modified to
emulate many of these.

Serial LCD displays are available in both text and graphic
versions. This project covers text displays with one to four lines and up to 40
columns. Initially, the displays will be limited to 80 total characters, a
limitation of the Arduino standard LCD library.

Since the serial LCD is a one wire device, all control of the LCD terminal must use command sequences. Here are the commands used in this project:

Except for the ?p### command they are identical to the PH Anderson, #117 chip. The start character for a command sequence is a '?', but this can be easily changed in the sketch, say to a '!'. The sketch below compiles, but some commands are missing.

One of the nice features of the #117 command set is that control can be accomplished using a PC termial program. In fact, using the Arduino IDE to update the code the built in terminal can be opened to test changes.The piggyback pcb can be modified and updated the same way.

Note: As of 10/08/12 the code was updated, as well as the schematic.The schematic changes were made to simplify the piggyback pcb layout. Because of this there were also changes to code. Several additional commands have been added and we will continue to add more.

Schematic Used with Solderless Breadboard:

The schematic above shows the parts which need to be added to the
solderless breadboard for this project. The headers in the schematic are the
the headers on the Arduino board. The piggyback board will require a different
schematic and include the atmega328, as well as, serial interface circuits and
jumpers.

The image below shows the Arduino Serial LCD connected to an
Arduino sending serial data at 9600 baude. The text being sent is
"Temperature" and "76.8" or "77.6", where the
word Temperature is sent once and the numbers sent alternately in the loop section of the sketch. Before
the numbers are sent the cursor is positioned at character column 14. The small
round object is a piezo speaker.